HI, I have a 1980 Tecumseh HS50 on a Craftsman snowblower. I've installed a new (superceded part # on it) replacement carb on it last year since I've gone thru 3 rebuilds on the old carb, and finally gave up on it (hard starting). With the new carb it starts fine on the 1st pull but I have a problem w/ the engine speed, it surges up & down in the midrange a bit, but mostly at high rpms. It seems to "pop" when decelerating from high rpms, too. I don't know how to get rid of any of these problems since it doesn't have any mixture screws. It's been like this since the install. Do you think it might be governor related? I need some tips on setting up the governor to make sure that's not the problem. The spark plug seems to look pretty normal so far, no signs of any extreme lean or rich mixture problems...btw it idles just fine.

My usual suggestion is to clean the bowl nut,2 holes at the bottom, one midway up and the center, I usually use the wire from a twist tie. Refer to the picture below. Have a good one. Geo
http://i190.photobucket.com/albums/z120/geogrubb/tec_bowl_nut.jpg

Although it sounds like it may be running a tad lean, it most definitely could be the governor if you did not adjust it when you installed the new carburetor. Try setting the static governor adjustment and see how it runs, if nothing changes then try geo's suggestion.

Best of Luck... :thumbsup:

...Try setting the static governor adjustment and see how it runs...

30yearTech, can give me a description on how to do that?

You can download the service manual for your engine at the link below. It describes the procedure pretty good, but if you still have any questions, just let me know.

http://www.cpdonline.com/692509.pdf

You can download the service manual for your engine at the link below. It describes the procedure pretty good, but if you still have any questions, just let me know.

http://www.cpdonline.com/692509.pdf

Thanks for that link. I read up on the L head governor section, it mentions that rpm settings are critical, I don't know what they should be. Does anyone have the so called Microfiche card#30? The engine did idle slower and seem to have a "slower" response to throttle changes vs. the old carb.
Engine specs:
Craftsman #s: 143.696082 SER 918 OB
Tecumseh #s: HS50-67181C
Sear's parts list shows the original carb# to this engine as 632107.